1. Field of the Technology
Embodiments relates generally to a display device and, and more particularly, to a pixel of the display device including an organic light emitting diode and an active matrix display device including the pixel.
2. Description of the Related Technology
Organic light emitting displays employ organic light emitting diodes (OLED). In operation, OLEDs emit light when an electric field is applied between an anode and a cathode, and the intensity of the emitted light can in turn be controlled by current and/or voltage applied to the anode and the cathode.
An OLED can be classified as a passive matrix OLED (PMOLED) or as an active matrix OLED (AMOLED), depending on the driving method employed.
Among the various types of OLEDS, AMOLED can be preferred for certain applications when considering factors such as the resolution, the contrast, and the operation speed of the OLED. A frame of an image displayed by an AMOLED includes a scanning period, during which image data is written into a pixel of an AMOLED. The frame further includes a light emission period, during which light is emitted from the pixel based on the written image data.
With the trend of increasing display panel size and resolution, the time it takes to scan, i.e., the time it takes to write image data to a pixel, becomes longer. As the scanning time increases, the ratio of the light emission period to an overall frame period decreases. To compensate for the reduced ratio, it is sometimes necessary to increase light emission luminance by increasing the power supply voltage, so that an average luminance is not degraded for the experience of a viewer. However, such an approach has downsides. For example, power consumption of the display device increases when power supply voltage is increased. Also, the driving current flowing through the pixels during light emission increases, and problems such as non-uniform luminance caused by a voltage drop across the display panel can be aggravated.
In particular, in the case where the display device displays a stereoscopic (i.e., a 3D) image, the ratio of the light emission period in one frame can be further reduced, and the aforementioned problems may become even more aggravated. For example, when the display device displays a stereoscopic image according to the NTSC (National Television System Committee) standard, the display has to display 60 frames of a left-eye image and 60 frames of a right-eye image for 1 second. Accordingly, the drive frequency of a stereoscopic image display device needs to be at least two times higher than the driving frequency of a general image display device.
Thus, there is a need for a pixel technology whose ratio of the light emission period to an overall frame time duration does not degrade with increasing size and resolution, nor when displaying a stereoscopic image.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.